I think what Mark_Solutions implies is that if the backup expires , even if the backup data are on disk, you can not use this backup image to do a restore. But you can import the data if you need.
If you want to copy the backups to USB disk I suggest the folowing
- Do not use USB for backups, Backup the data to a regular disk and then replicate to USB.
- As Mark_Solutions say, netbackup is unable to delete expired backup images from a disk that is not attached to the system. So stick labels to the disk with the backups and their expiration dates. Netbackup will delete only the backup metadata from catalog.
- Attach the disk to the system when backups are near expiration so netbackup can delete the backup images or manually delete the backups from the disk after the backups are expired. if you fail to delete expired backups the disk eventually will get full with garbage.
- based on the previews, do not swap a disk with another that already contains unexpired backups. it will make your life easier.
- I think it will be better if you create multiple basic storage units, one for every disk and give to every USB disk a different drive letter. It will be easier for you to track the backups on every disk.
